Lpg fuel supply systems for internal combustion engines



Nov. 30, 1965 1 SCHUNK LPG FUEL SUPPLY SYSTEMS FOR INTERNAL coMBusTxoNENGINES Filed Nov. 22, 1963 ATTYS.

United States Patent O 3,220,393 LPG FUEL SUPPLY SYSTEMS FR INTERNALCOMBUSTION ENGINES Lawrence J. Schlink, Sharon, Pa., assigner to GeneralAmerican Transportation Corporation, Chicago, Ill., a corporation of NewYork Filed Nov. 22, 1963, Ser. No. 325,608 4 Claims. (Cl. 12S- 120) Thepresent invention relates to LPG fuel supply systems for internalcombustion engines, and particularly to such systems employing propaneas the LPG fuel, and specifically to such systems incorporated inrailway cars utilizing internal combustion engine driven equipment forheating, cooling or similar purposes.

In a conventional railway refrigerator car, the refrigeratin-g equipmentis driven by an internal combustion engine operating on propane andsupplied from a pressure tank that is subject to the ambienttemperature. The refrigerating equipment is capable of direct operationfor cooling the lading in warm weather and of heat-pump operation forheating the lading in cold weather; whereby it is equally necessary tooperate the refrigerating equipment in extremely cold weather, as it isin extremely hot weather, since a lading will be damaged by freezing incold weather or by spoiling in hot weather.

In the system, the lower portion of the fuel tank contains a body ofliquid propane and the upper portion of the fuel tank contains aquantity of vaporous propane, with these two states Iof the propane inequilibrium under the prevailing pressure-temperature conditions in thefuel tank. Propane has substantial volatility over the ambienttemperature ran-ge; however, at temperatures of about 30 F. and below,the vapor pressures are relatively low, and at temperatures of about 100F. and above, the vapor pressures are relatively high, and attemperatures in the general range of 50 F. to 90 F., the vapor pressuresare moderate. It is highly desirable to operate the internal combustionengine on a combustible mixture 'of vaporous propane and air; whereby attemperatures above about 50 F., adequate vaporous propane is ordinarilygenerated in the fuel tank to supply the requirements of the engine;however, at temperatures below about 50 F., the rate of generation ofvaporous propane in the fuel tank is inadequate to supply therequirements of the engine.

In order to overcome this diiculty, it is conventional practice toincorporate in such railway refrigerator car a preheater for vaporizingthe liquid propane, so as to supply the vaporous propane requirements ofthe engine during cold weather, as explained above. However, thepreheater is ordinarily of the open-flame type that requires startingwith vaporous propane. Hence, in exceedingly cold weather, below about30 F., substantial difficulty is encountered in startin-g the operationof the preheater. Moreover, such preheaters, although widely used insuch railway refrigerator cars, are not only troublesome in exceedinglycold weather, as explained above, but they constitute a major firehazard, since the openflame burning of propane vapor is altogetherunsatisfactory from the standpoint of safety.

While the foregoing discussion has been set forth in terms of propane,as the LPG fuel, the same considerations apply to butane and to theother members of this class of petroleum fuels.

Accordingly, it is a general object of the present invention to providean improved and simplified system for supplying vaporous LPG fuel to aninternal combustion engine that does not require a pheheater of theopenflame type.

Another object 'of the invention is to provide an irnvproved LPG fuelsupply system for an internal combus- Mice tion engine, wherein facilityis provided for starting the engine with the initial quantity ofvaporous fuel in the associated fuel tank, and including a vaporizerarranged in good heat-exchange relation with the engine, whereby theheat produced by the initial running of the engine renders operative thevaporizer, so that the liquid fuel in the fuel tank may be converted tovaporous fuel in order to sustain the operation of the engine.

A further object of the invention is to provide a fuel supply system ofthe character described, wherein the engine may be readily started inthe coldest weather, and wherein the running engine then produces itsown supply of vaporous fuel from liquid fuel in the fuel tank, wherebycontinued running of the engine is assured.

A further object of the invention is to provide a fuel supply system ofthe character described, wherein the running engine renders effectivethe vaporizer to produce vaporous fuel in a quantity greatly in excessof the requirements of the engine, so that the excess vaporous fuel maybe supplied to other devices or auxiliaries that are 'operated byvaporous fuel.

A still further object of the invention is to provide a fuel supplysystem of the character described that incorporates safety devicesrendering it altogether safe in operation and simple to control.

Further features of the invention pertain to the particular connectionand arrangement of the elements of the fuel supply system, whereby theabove-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specication, taken inconnection with the accompanying drawing, in which:

The single figure is a diagrammatic illustration of an LPG fuel supplysystem for an internal combustion engine and embodying the presentinvention.

Referring now to the drawing, the fuel supply system there illustratedand embodying the features of the present invention, comprises a fuelstorage tank 10' of the pressure type adapted to contain a LPG fuel,such as propane. As illustrated, the tank 10 is arranged in asubstantially horizontal position, whereby the lower portion thereofcontains a body 11a of the fuel in the liquid state and the upperportion thereof contains a quantity 11b of the fuel in the vaporousstate, with the body 11a and the quantity 11b in the respective liquidand vaporous states in equilibrium with each other under the prevailingpressure-temperature conditions in the tank 10, in a well-known manner.Thus, it will be appreciated, that should the pressure of the quantity11b be reduced, some of the fuel in the body 11a would boil off toproduce or generate some additional vaporous fuel, so as simultaneouslyto' increase the pressure of the quantity 11b and to cool both the body11a and the quantity 11b, thereby to establish the equilibrium mentionedunder the new conditions of pressure-temperature in the fuel in the tank10. Since propane is characterized by high volatility over the ambienttemperature range, there is always some of the fuel in the vaporousst-ate, as long as there is a supply thereof in the liquid state at atemperature above the boiling point. However, the tank 10 is underrelatively low pressure at temperatures of about 30 F. and below, and isunder relatively high pressure at temperatures of F. and above, as iswell understood.

Also, the system comprises an internal combustion engine 12 of anysuitable type that is operative upon a combustible mixture of vaporouspropane and air; which engine 12 includes a vaporous fuel supply pipe 13and an exhaust gases pipe 14, as well as a carburetor device 15 that isconnected to'the vaporous fuel supply pipe 13 and that is operative tomix air with the vaporous fuel and to inject the resulting combustiblemixture into the cylinders of the engine 12 in proper timed sequence inthe cycle of operation thereof, all in a conventional manner. Also, ablower 16 is operated by the engine 12; which blower 16 is provided witha casing 17 having an inlet 18 and an outlet 19. The blower 16 isoperative to draw cooling air into the outlet 18, to circulate thecooling air through the casing 17 and into good heatexchange relationwith the block of the engine 12, and then to discharge the resulting hotair from the casing 17 through the outlet 19 for a purpose more fullyexplained hereinafter.

A first fuel outlet pipe 20 is connected to the top of the tank incommunicating relation with the quantity 11b of vaporous fuel in theupper portion of the tank 10; and a second fuel outlet pipe 21 issecured in place in an opening provided in the top of the tank 10 andprojects downwardly thereinto and provided With an open bottom enddisposed adjacent to the bottom of the tank 10 and in communicatingrelation with the body 11a of liquid fuel in the lower portion of thetank 10. The first fuel outlet pipe 20 is connected by a manuallyoperable service valve 22 to supply a pipe 23; and the second fueloutlet pipe 21 is connected by a manually operable service valve 24 to asupply pipe 25. The supply pipe 23 is protected against over pressure bya connected high pres" sure relief valve 26; and, similarly, the supplypipe 25 is protected against over pressure by a connected high pressurerelief valve 27.

Also, the system comprises a manifold 28, and a main vapor feed pipe 29.A single stage pressure regulator 30 is provided that includes ahigh-pressure inlet connected to the manifold 28 and a low-pressureoutlet connected to the main vapor feed pipe 29. The vaporous feedsupply pipe 13 extending to the carburetor 15 is connected to themanifold 28; while the main vapor feed pipe 29 extends to supply otherdevices or auxiliaries, not shown, that require the supply thereto ofvaporous fuel at modest pressure. A back pressure valve 31 is providedthat includes an inlet connected to the manifold 28 and an outletconnected to the supply pipe 23.

Further, the system comprises manually operable valve mechanism 40,including a first valve casing 41 housing a rotatable ported block 42, asecond valve casing 43 housing a rotatable ported block 44, and amanually operable handle lever 45 mounted for pivotal movements betweenstart and run positions and commonly operatively connected to the twoported blocks 42 and'44, as indicated at 46. The casing 41 has first andsecond inlets respectively connected to the supply pipes 23 and 25, andan outlet connected to a transfer pipe 47; while the casing 43 has aninlet connected to the transfer pipe 47, and first and second outletsrespectively connected to the manifold 28 and to a pipe 51. Also, acheck valve 52 is provided that has an inlet connected to the pipe 51and an outlet connected to a pipe 53. In the valve mechanism 40, whenthe manual lever 45 occupies its start position, the block 42 isactuated to the position illus` trated, so that the supply pipe 23 isconnected by the block 42 to communicate with the transfer pipe 47, andso that the block 42 closes the supply pipe 25, and the block 44 isactuated to the position illustrated, so that the transfer pipe 47 isconnected by the block 44 to the manifold 28 and so that the block 44closes the pipe 51. On the other hand, when the manual lever 45 occupiesits run position, the block 42 is actuated to connect the supply pipe 25to the transfer pipe 47 and to close the connection between the supplypipe 23 and the casing 41, and the block 44 is actuated to connect thetransfer pipe 47 to the pipe 51 and to close the connection between themanifold 28 and the casing 41.

Further, the system -comprises a vaporizer 62 having an inlet connectedto the pipe 53 and an Qutlet connected to the manifold 23. The exhaustgases pipe 14 from the engine 12 includes a heat'exchanger 61operatively associated in good heat-exchange relation with the vaporizer60. Specifically, a casing 62 is provided that encloses the vaporizer 60and the heat exchanger 61; which casing 62 is provided with an inletconnected to the outlet 19 from the blower 16, and an outletcommunicating with the atmosphere.

Considering now the mode of operation of the system, and assuming thatthe engine 12 is to be started, when it is cold, and that the weather iscold, so that only a relatively loW pressure is present in the storagetank lil, the manual lever 45 is operated into its start position, andthe service valves 22 and 24 are operated into their open positions.With the manually operable valve mechanism 40 in its start position, thevaporous fuel from the quantity 11b proceeds from the upper portion ofthe tank 10 via the elements 20, 22, 23, 41, 47 and 43 into the manifold28; from the manifold 28 the vaporous fuel is throttled by the regulator30 into the main vapor feed pipe 29 at a predetermined modest pressure;and from the manifold 28 the vaporous fuel proceeds directly into thecarburetor 15. In the carburetor 15, a combustible mixture is producedby the addition of air into the vaporous fuel; and this combustiblemixture is supplied to the cylinders of the engine 12. It may be assumedthat the engine 12 is cranked or started promptly in a conventionalmanner; whereby heat is developed in the block of the engine 12 and heatis rejected from the engine 12 via the exhaust gases passing therefromthrough the exhaust gases pipe 14. The blower 16 is operated by theoperating engine 12, so that heat is removed from the engine block bythe cooling air circulated by the blower 16 causing hot air to pass viathe outlet 19 into the casing 62; and, of course, the heat exchanger 61is heated by the hot exhaust gases passing therethrough, since theelement 61 is arranged in the exhaust gases pipe 14, as previouslynoted. The hot air passing into the casing 62 is directed intoheat-exchange relation with the heat exchanger 61, so that thetemperature of the hot air mentioned is substantially elevated. Theexceedingly hot air then passes into heat-exchange relation with thevaporizer 60 and thence to the atmosphere; whereby the temperature ofthe vaporizer 60 is elevated in an obvious manner.

After the operator cranks or starts the engine 12, and determines thatit is operating satisfactorily at steady state, he shifts the lever 45from its start position to its run position. With the manually operablevalve mechanism 40 in the run position, the liquid fuel from the body11a proceeds from the lower portion of the tank 10 Via the elements 21,24, 25, 41, 47, 43, 51, 52 and 53 into the vaporizer 60. In the hotvaporizer 60, the liquid fuel is immediately flashed into vaporous fueland proceeds into the manifold 28 from which it is throttled into themain vapor feed pipe 29. Also, from the manifold 28 the vaporous fuel issupplied via the vaporous fuel supply pipe 13 to the carburetor 15;whereby the operation of the engine 12 is sustained, in an obviousmanner.

Since the operator may shift the manual lever 45 from its start positioninto its run position very shortly after operation of the engine 12 isstarted, there is always enough vaporous fuel in the quantity 11b, evenin subzero weather, for the present purpose; however, in cold weather,the operator should so shift the manual lever 45 promptly, as it isapparent that the accumulated quantity 11b of vaporous fuel is consumedfaster by the engine 12 than it is being automatically generated in thetank 10. In moderate and warm weather, the operator can take his timeabout shifting the manual level 45, as explained above, without dangerof consuming all of the available vaporous fuel by the running engine12; however, it is contemplated that the operator will always shift themanual lever 45 promptly, after he starts the engine 12 and determinesthat it is running satisfactorily. Thus, the

manual lever 45 always occupies its run position, during the normalrunning of the engine 12.

In the normal running of the engine 12, the check valve 52 prevents highpressure in the manifold 28 and in the vaporizer 60 from causingblow-back through the pipe 53 and into the pipe 51, so as to preventliquid fuel from moving backwards from the pipe 51 through the elements43, 47, 41, 25, 24 and 21 back into the body 11a contained in the tank10. On the other hand, in the event of an abnormally high pressure ofthe vaporous fuel in the manifold 28, the back pressure valve 31 opensto throttle the vaporous fuel from the manifold 28 back into 'the supplypipe 23; whereby the same may pass through the elements 22 and 20 backinto the quantity 11b contained in the upper portion of the tank 10. Ofcourse, the relief valves 26 and 27 serve the usual high pressure relieffunctions with respect to the respective supply pipes 23 and 25,effecting the escape of the high pressure vaporo us fuel to theatmosphere in the event of abnormally high and dangerous pressures inthe respective supply pipes 23 and 25.

When operation of the engine 12 is to be arrested, the service valves 22and 24 are closed to cut-off the supply of vaporous fuel from the fueloutlet pipe to the supply pipe 23 and to cut-off the supply of liquidfuel from the fuel outlet pipe 21 to the supply pipe 25. Also, at thistime, the manual lever 45 is ordinarily returned back into its startposition, so as again to condition the system for subsequent restartingof the engine. Of course, closure of the services valves 22 and 24insures that no fuel is supplied 'into the manifold 28 whereby operationof the engine 12 and the other devices or auxiliaries connected to themain vapor supply pipe 29 are arrested.

As previously explained, the engine 12 may drive an associatedrefrigeratng machine capable of both direct operation to effect coolingof a lading chamber and heatpump operation to effect heating of thelading chamber, such, for example, as disclosed in U.S. Patent No.2,887,853, granted on May 26, 1959 to Paul Talmey; whereby, as disclosedin the Talmey Patent, the refrigerating machine, the engine 12, the fuelstorage tank 10, and the other elements of the fuel supply system wouldthen be incorporated in the associated railway refrigerator car, notshown.

While the present fuel supply system is ideally suited for use in arailway refrigerator car, as explained above, the same is of generalutility; whereby in the interest of brevity no showing of the details ofthis particular application is considered necessary. Furthermore, otherapplications of the fuel supply system to internal combustion enginesdriving other types of loads are equally obvious and well understood.The system also has the advantage that it employs heat in the vaporizer62 that is rejected by the engine 12, thereby increasing the overallefiiciency of the system, as compared to conventional systems employingfuel burners for the purpose of vaporizing the liquid fuel, aspreviously explained.

In view of the foregoing, it is apparent that there has been provided afuel supplysystern for an internal combustion engine operating on LPGfuel in the vapor phase, with admixed air, that insures easy starting ofthe engine, even in the coldest weather, and that insures proper runningof the engine after starting thereof. Also, the system incorporates thenecessary safety devices and arrangements so that safe and properoperation of the engine is assured, even though the engine is unattendedfor long time intervals.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications that fall within the truespirit and scope of the invention.

What is claimed is:

1. In combination, a tank adapted to contain liquefied petroleum fuelthat is characterized by high volatility so that it is under relativelylow vapor pressure at 30 F. and under relatively high vapor pressure atF., whereby within this pressure range the lower portion of said tankmay contain a body of the fuel in the liquid state and the upper portionof said tank may contain a quantity of the fuel in the vapor state withthe two states of the fuel in equilibrium under the prevailingpressuretemperature conditions thereof in said tank, a first fuel outletpipe connected to the upper portion of said tank above the operativerange of liquid fuel levels therein and communicating with the quantityof vaporous fuel in said tank, a second fuel outlet pipe connected tothe lower portion of said tank below the operative range of liquid fuellevels therein and communicating with the body of liquid fuel in saidtank, a manifold, an internal combustion engine provided with a vaporousfuel supply pipe connected to said manifold, a liquid fuel vaporizerhaving an inlet and an outlet and arranged in good heat-exchangerelation 4with said engine, the outlet of said vaporizer being connectedto said manifold, valve mechanism connected to said first and secondfuel outlet pipes and to said manifold and to the inlet of saidvaporizer, said valve mechanism having a start position and a runposition, said valve mechanism in its start position opening said firstfuel outlet pipe to said manifold and closing said second fuel outletpipe from the inlet of said vaporizer, said valve mechanism in its runposition closing said first fuel outlet pipe from said manifold andopening said second fuel outlet pipe to the inlet of said vaporizer, andmeans for selectively operating said valve mechanism between its startposition and its run position. p

2. In combination, a tank adapted to contain liquefied petroleum fuelthat is characterized by high volatility so that it is under relativelylow vapor pressure at 30 F. and under relatively high vapor pressure at100 F., whereby Within this pressure range the lower portion of saidtank may contain a body of the fuel in the liquid state and the upperportion of said tank may contain a quantity of the fuel in the vaporstate with the two states of the fuel in equilibrium under theprevailing pressure-temperature conditions thereof in said tank, a firstfuel outlet pipe connected to the upper portion of said tank above theoperative range of liquid fuel levels therein and communicating with thequantity of vaporous fuel in said tank, a second fuel outlet pipeconnected to the lower portion of said tank below the operative range ofliquid fuel levels therein and communicating with the body of liquidfuel in said tank, a manifold, a back-pressure valve having ahigh-presure inlet connected to said manifold and a low-pressure outletconnected to said first fuel outlet pipe, an internal combustion engineprovided with a vaporous fuel supply pipe connected to said manifold, aliquid fuel vaporizer having an inlet and an outlet and arranged in goodheat-exchange relation with said engine, the outlet of said vaporizerbeing connected to said manifold, valve mechanism connected to saidfirst and second fuel outlet pipes and to said manifold and to the inletof said vaporizer, said valve mechanism having a start position and arun position, said valve mechanism in its start position opening saidfirst fuel outlet pipe to said manifold and closing said second fueloutlet pipe from the inlet of said vaporizer, said valve mechanism inits run position closing said first fuel outlet pipe from said manifoldand opening said second fuel outlet pipe to the inlet of said vaporizer,and means for selectively operating said valve mechanism between itsstart position and its run position.

3. In combination, a tank adapted to contain liquefied petroleum fuelthat is characterized by high volatility so that it is under relativelylow vapor pressure at 30 F. and under relatively high vapor pressure at100 F.,

whereby within this pressure range the lower portion of said tank maycontain a body of the fuel in the liquid state and the upper portion ofsaid tank may contain a quantity of the fuel in the vapor state with thetwo states of the fuel in equilibrium under the prevailingpressuretemperature conditions thereof in said tank, a first fuel outletpipe connected to the upper portion of said tank above the operativerange of liquid fuel levels therein and communicating with the quantityof vaporous fuel in said tank, a second fuel outlet pipe connected tothe lower portion of said tank below the operative range of liquid fuellevels therein and communicating with the body of liquid fuel in saidtank, a manifold, an internal combustion engine provided with a vaporousfuel supply pipe connected to said manifold, a liquid fuel vaporizerhaving an inlet and an outlet and arranged in good heatexchange relationwith said engine, the outlet of said vaporizer being connected to saidmanifold, a check valve having an inlet and an outlet, the outlet ofsaid check valve being connected to the inlet of said vaporizer, valvemechanism connected to said first and second fuel outlet pipes and tosaid manifold and to the inlet of said check valve, said valve mechanismhaving a start position and a run position, said valve mechanism in itsstart position opening said first fuel outlet pipe to said manifold andclosing said second fuel outlet pipe from the inlet of said check valve,said valve mechanism in its run position closing said first fuel outletpipe from said manifold and opening said second fuel outlet pipe to theinlet of said check valve, and means for selectively operating saidvalve mechanism between its start position and its run position.

4. In combination, a tank adapted to contain liquefied petroleum fuelthat is characterized by high volatility so that it is under relativelylow vapor pressure at 30 F. and under relatively high vapor pressure at100 F., whereby within this pressure range the lower portion of saidtank may contain a body of the fuel in the liquid state and the upperportion of said tank may contain a quantity of the fuel in the vaporstate with the two states of the fuel in equilibrium under theprevailing pressure-temperature conditions thereof in said tank, a firstfuel outlet pipe connected to the upper portion of said tank above theoperative range of liquid fuel levels therein and com-v municating withthe quantity of vaporous fuel in said tank,

a second fuel outlet pipe connected to the lower portion of said tankbelow the operative range of liquid fuel levels therein andcommunicating with the body of liquid fuel in said tank, a manifold, aninternal combustion engine provided with a vaporous fuel supply pipe andan exhaust gases pipe, said vaporous fuel supply pipe being connected tosaid manifold, a liquid fuel vaporizer having an inlet and an outlet, acasing enclosing said vaporizer, said exhaust gases pipe extendingthrough said casing, means including a blower for circulating coolingair over said engine and thence through said casing, wherein the hotcirculated air introduced into said casing is first circulated over saidexhaust gases pipe extending therethrough and then into heat-exchangerelation with said vaporizer enclosed therein, the outlet of saidvaporizer being connected to said manifold, valve mechanism connected tosaid rst and second fuel outlet pipes and to said manifold and to theinlet of said vaporizer, said valve mechanism having a start positionand a run position, said valve mechanism in its start position openingsaid rst fuel outlet pipe to said manifold and closing said second fueloutlet pipe from the inlet of said vaporizer, said valve mechanism inits run position closing said first fuel outlet pipe from said manifoldand opening said second fuel outlet pipe to the inlet of said vaporizer,and means for selectively operating said valve mechanism between itsstart position and its run position.

References Cited bythe Examiner UNITED STATES PATENTS mercial CarJournal; January 1934; pages 2O and 21.

MARK NEWMAN, Primary Examiner.

RICHARD B. llILKINSON, Examiner.

1. IN COMBINATION, A TANK ADAPTED TO CONTAIN LIQUEFIED PETROLEUM FUELTHAT IS CHARACTERIZED BY HIGH VOLATILITY SO THAT IT IS UNDER RELATIVELYLOW VAPOR PRESSURE AT 30*F. AND UNDER RELATIVELY HIGH VAPOR PRESSURE AT100*F., WHEREBY WITHIN THIS PRESSURE RANGE THE LOWER PORTION OF SAIDTANK MAY CONTAIN A BODY OF THE FUEL IN THE LIQUID STATE AND THE UPPERPORTION OF SAID TANK MAY CONTAIN A QUANTITY OF THE FUEL IN THE VAPORSTATE WITH THE TWO STATES OF THE FUEL IN EQUILIBRIUM UNDER THEPREVAILING PRESSURETEMPERATURE CONDITIONS THEREOF IN SAID TANK, A FIRSTFUEL OUTLET PIPE CONNECTED TO THE UPPER PORTION OF SAID TANK ABOVE THEOPERATIVE RANGE OF LUQID FUEL LEVELS THEREIN AND COMMUNICATING WITH THEQUANTITY OF VAPOROUS FUEL IN SAID TANK, A SECOND FUEL OUTLET PIPECONNECTED TO THE LOWER PORTION OF SAID TANK BELOW THE OPERATIVE RANGE OFLIQUID FUEL LEVELS THEREIN AND COMMUNICATING WITH THE BODY OF LIQUIDFUEL IN SAID TANK, A MANIFOLD, AN INTERNAL COMBUSTION ENGINE PROVIDEDWITH A VAPOROUS FUEL SUPPLY PIPE CONNECTED TO SAID MANIFOLD, A LIQUIDFUEL VAPORIZER HAVING AN INLET AND AN OUTLET AND ARRANGED IN GOODHEAT-EXCHANGE RELATION WITH SAID ENGINE, THE OUTLET OF SAID VAPORIZERBEING CONNECTED TO SAID MANIFOLD, VALVE MECHANISM CONNECTED TO SAIDFIRST AND SECOND FUEL OUTLET PIPES AND TO SAID MANIFOLD AND TO THE INLETOF SAID VAPORIZER, SAID VALVE MECHANISM HAVING A START POSITION AND ARUN POSITION, SAID VALVE MECHANISM IN ITS START POSITION OPENING SAIDFIRST FUEL OUTLET PIPE TO SAID MANIFOLD AND CLOSING SAID SECOND FUELOUTLET PIPE FROM THE INLET OF SAID VAPORIZER, SAID VALVE MECHANISM INITS RUN POSITION CLOSING SAID FIRST FUEL OUTLET PIPE FROM SAID MANIFOLDAND OPENING SAID SECOND FUEL OUTLET PIPE TO THE INLET OF SAID VAPORIZER,AND MEANS FOR SELECTIVELY OPERATING SAID VALVE MECHANISM BETWEEN ITSSTART POSITION AND ITS RUN POSITION.